[clang] [Clang] Implement P2280R4 Using unknown pointers and references in constant expressions (PR #95474)

[Shafik Yaghmour via cfe-commits]

shafik wrote:

@ahatanak it seems like trunk now return 4 for all cases: https://godbolt.org/z/ds4ofbv6d I will have to look into the first two cases to understand what is going on better



https://github.com/llvm/llvm-project/pull/95474